1. Field of the Invention
The present invention relates to a fan and, more particularly, to a micro fan realized by micro electromechanical system technology.
2. Description of the Related Art
A conventional self-assembly micro fan is described in Taiwan Patent No. 1275563 entitled “SELF-ASSEMBLY STRUCTURE CONSTRUCTED BY POLYIMIDE FILM,” which is a micro fan realized by self-assembly technique of micro electromechanical systems technology. Referring to FIG. 1, the conventional micro fan 9 includes a body 91, a plurality of blades 92, and a plurality of flexible joints 93. The body 91 has a hub 911 positioned at a center of an outer ring 913 and connecting with the outer ring 913 by a plurality of actuators 912. The blades 92 are radially arranged along an outer periphery of the outer ring 913. The plural flexible joints 93 respectively connect between the blades 92 and the outer ring 913.
Now please turn to FIG. 2. The flexible joints 93 of the conventional micro fan 9 realized by self-assembly technique is constructed by polyimide film. In manufacture of the micro fan 9, the flexible joints 93 are performed with a reflow process in an oven and thus bent owing to thermal contraction. Consequently, through the thermal-caused bending, each blade 92 is lifted and pivots on the flexible joint 93 connected therewith and has an angle relative to a radial direction of the body 91, and hence the manufacture of the micro fan 9 is accomplished.
Generally, for any one of the blades 92, because the flexible joint 93 linking the blade 92 and the outer ring 913 is only a squared member while the blade 92 and the outer ring 913 merely connect with two ends of the flexible joint 93 respectively, an area for combination between the blade 92 and the flexible joint 93 is obviously limited, and thus the angle between the blade 92 and the radial direction of the body 91 is also limited. Furthermore, owing to the crude combination between the blade 92 and the flexible joint 93, the blade 92 can only be simply lifted without curvature or an inclined inner edge, and thus the air-driving efficiency of the conventional micro fan 9 is limited too. Hence, there is a need for an improvement over the conventional micro fan 9.